Impact hammer for hammermills



Sept. 21, 1965 B. c. MILLER 3,207,448

IMPACT HAMMER FOR HAMMERMILLS Filed July 10, 1963 INVENTOR Y ov1 C. M LLEl-R.

ATTORNEYS United States Patent 3,207,448 IMPACT HAMMER FOR HAMMERMILLS Boyd C. Miller, 1123 W. Henderson St, Salisbury, N.C. Filed July 10, 1963, Ser. No. 294,053 7 Claims. or. 241 197 This invention relates to impact hammers for hammermills and the like and, more specifically, to an improved hammer of the type having a reversible and replaceable tip detachably connected to its shank.

A primary object of this invention is the provision of an impact hammer of the type described in which the tip is retained securely upon the shank and is not subject to accidental disengagement while the hammer is in use, but in which the tip is capable of being readily disconnected and removed from the shank when desired, as when the tip becomes worn to such an extent that its reversal or replacement is necessary, without the us of any tools or extraneous devices whatsoever and without having to first remove the hammer from its supporting shaft.

A related and more specific object is the provision of an impact hammer of the type described in which the components detachably connecting the tip to the shank are permanently housed within and associated with either the tip or the shank, and are thus incapable of being either damaged while the hammer is in use or of being lost or misplaced when the tip is disconnected from the shank for purposes of reversal or replacement.

Another related and still more specific object is the provision in an impact hammer of the type described of spring-biased, self-releasing detent means for detachably connecting the tip and shank of the hammer.

Another object is the provision of an impact hammer possessing and realizing the hereinbefore noted advantages and benefits, and which is additionally of rugged and durable, but highly economical, construction.

Still other objects and advantages will be in part evident and in part pointed out hereinafter in the following description of an illustrative embodiment of the invention, which should be read in conjunction with the accompanying drawing, in which:

FIGURE 2 is a side elevation of an impact hammer embodying the invention;

FIGURE 2 is a front elevation of the hammer of FIG- URE 1;

FIGURE 3 is an exploded and enlarged perspective view of the hammer of FIGURE 1; and

FIGURE 4 is an enlarged vertical section taken approximately along the line 44 of FIGURE 2.

Refer-ring more particularly to the drawing, the hammer identified in its entirety in FIGURES 1 and 2 by the numeral consists generally of an elongate shank member 12 having a reversible and replaceable tip member 14 detachably connected to its outer end by mating interfacial tongue and groove means 16 and by detent means 18. Hammer 10 is, of course, for-med of steel or other high-strength, wear-resistant material.

As is conventional, a transverse bore 26 is provided through the inner end of shank 12 of hammer 10 for the reception of the supporting hammermill shaft (not shown) about which the hammer is swung or pivoted. Shank 10 is generally T-shaped, having at its outer end an elongate rail-like section 2.2 which extends parallel to the axis of bore 20, and therefore normal to the direction of pivotal movement of the hammer 10, and which includes an innermost flange portion 24 and an outermost head portion 26 interconnected by an integral web portion 28. Surfaces 30, 30' of flange .portion 24, 32 and 32' of web portion 28, and shoulders 34, 34' surfaces 36, 36' and terminal surface 38 of head portion 26 collectively define one-half of the interface and the tongue and groove means 16 between shank 12 of hammer 10 and 3,207,448 Patented Sept. 21, 1965 the replaceable and reversible tip 14 to be now described.

Tip 14 of hammer 10 is of massive, generally rectangular construction and shape, including major front and rear faces 40, 40', respectively, side faces 42, 42', an innermost face 43, and an outermost or terminal face 44. A departure from the generally rectangular shape of tip tip 14, and also a highly desirable and significant feature thereof, are the flared projections 46, 46' formed integral with and along the outermost areas of front and rear faces 40, 40, respectively. The provision of projections 46, 46' at these areas of maximum wear greatly lengthens the useful life of tip 10 and prolongs the time before which its reversal or replacement i necessary.

The length of tip 14 is the same as the length of raillike section 22 of shank 12, and extending along the entire length of its innermost face 43 is a centrally disposed groove 48 having an innermost portion defined by surfaces 50, 50, and an outermost, undercut portion defined by the curved surfaces 52, '52 and the planar surface 54. The surfaces of innermost face 43 of tip 14 bordering groove 48, and the surfaces 50, 50, 52, 52 and 54 of the groove, collectively define the remaining onehalf of the interface and the tongue and groove means 16 between shank 12 of hammer 10 and tip 14. Thus, when tip 14 and rail-like section 22 of shank 12 are properly and fully connected with the tongue and groove means 16 thereof in mating relationship, as is shown in FIG- URES 1, 2 and 4, there is contiguity between the surfaces of innermost face 43 of the former and surfaces 30, 30' of flange portion 24 of the latter, between surfaces 50, 50' of groove 48 of the former and surfaces 32, 32' of web portion 28 of the latter, between curved surfaces '52, 52 of groove 48 of the former and shoulders 34, 34' and surfaces 36, 36' of head portion 26 of the latter, and between surface 54 of groove 48 of the former and surface 38 of head 26 of the latter. Although having the contiguous areas noted, actual contact preferably exists only between shoulders 34, 34' of head portion 26 of rail-like section 22 of shank 12 and surfaces 52, 52' of groove 48 of tip 14 (see FIGURES 1 and 4), there preferably being a slight clearance between the other contiguous surfaces to facilitate tip 14s connection to and disconnection from shank 12 without binding.

It will be appreciated that their heretofore described construction permits tip 14 and shank 12 to be readily connected and disconnected, assuming in the former case the previous alinement of portions 26, 28 of rail-like section 22 of the shank with groove 48 of the tip, merely by sliding the tip and shank relative to each other longitidinally of tongue and groove means 16. This relative movement is usually most conveniently elfected by sliding tip 14 relative to shank 12, and it should be noted that it is possible for the movement to be directed toward either desired one of the side faces 42, 42' of the tip: that is tip 14 can be connected to and disconnected from either desired side of shank 12. This is deemed a significant and advantageous feature since it permits tip 14 to be connected and disconnected quickly and easily without the necessity for removing the hammer 10 from its supporting shaft, or otherwise varying its position relative to the shaft, even when another hammer or other obstruction is closely adjacent one of its sides.

When tip 14 is properly connected to shank 12 as shown in FIGURE 2, it will be appreciated that tongue and groove means 16 prohibits all movement of the tip relative to the shank except movement longitudinally of tongue and groove means 16 or parallel to the axis of bore 20. And since the travel of hammer 10 about its supporting shaft (not shown) is normal thereto, there is little tendency for this latter movement to occur while the hammer is in use. However, to avoid all possibility of tip 14 being inadvertently disconnected from shank 12 while hammer is in use, while still permitting the tip to be conveniently connected to and disconnected from the shank when desired, there is provided the self-releasing detent means 18 hereinbefore noted and now to be described in detail. Referring now primarily to FIGURES 3 and 4, provided within shankmember 12 and tip member 14 are interfacial recesses 56, 58, respectively, which are relatively disposed so as to be in alinement with each other when the tips and shank are in their fully connected condition illustrated in FIGURE 2. As shown, recess 56 consists of a bore disposed centrally of rail-like section 22 of shank 12 and extending normal to the longitudinal axis of section 22 and to the plane of surface 38 of head portion 26 thereof. The length of recess or bore 56 is such that its innermost end is disposed within flange portion 24 of rail-like section 22. The outermost end of recess or bore 56 opens through surface 38 of head portion 26 of rail-like section 22, which surface forms, as noted previously, a portion of the interface between shank 12 and tip 14.

Permanently mounted, as by means of a press-fit or adhesion, within recess or bore 56 is a tubular housing 60 having a closed innermost end and an open router-most end. The length of housing 60 is such that when the same is fully received within recess or bore 56, its open outermost end is substantially even or co-planar with surface 38 of head portion 26. An inturned lip 62 is provided integral and co-extensive with the open outermost end of housing 60, and within the housing there is provided a detent element in the form of a hardened sphere or ball 64, the diameter of which is either the same as or only slightly less than the inner diameter of that portion of housing 60 which includes lip 62. The inner diameter of housing 60 at lip 62 being less than elsewhere along its length, the inner diameter of the housing elsewhere along its length is greater than the diameter of ball 64: by way of illustration, it has been found satisfactory to provide with a ball 64 of one-half inch diameter an inner diameter of that same dimension for housing 60 at lip 62, and an inner diameter of seventeen thirty-seconds of an inch elsewhere along the length of housing 60. By virtue of the foregoing relationship of dimensions, it will be apparent that while ball 64 is captured within housing 60 by lip 62, it is free for rotative movement and for movement not only longitudinally of housing 60 but also partially beyond the open, outermost end of the housing, and therefore for movement partially through and beyond the interfacial surface 38 of head portion 26. Biasing means in the form of a compression spring 66 and an abutment member in the form of a flat washer 68 are disposed Within housing 60 intermediate its closed end and ball 64, with the washer 68 between spring 66 and the ball, and bias ball 64 toward and partially through the open outermost end of the housing while still permitting its rotative movement and its movement toward the closed end of the housing.

Interfacial recess 58 of tip 14 is formed centrally of surfaces 54 of groove 48 of the tip with a curved surface adapted to matingly receive and seat a minor portion of the detent element carried by shank 12. In the case of the spherical detent element or ball 64 shown, therefore, the surface of recess 58 is that of a portion of a sphere equal in diameter to ball 64. Preferably the surface of recess 58 is hemispherical or only slightly less than hemispherical. When the recess 58 is perfectly hemispherical, as in the illustrative embodiment shown in which the same is formed with a one-quarter inch spherical. radius, the maximum seating engagement between the ball and the recess is obtained while still only a minor portion of the ball is seated within the recess due to the heretofore mentioned clearance between surfaces 38 and 54.

When shank 12 and tip 14 are fully connect-ed as shown in FIGURE 2, recesses 56 and 58 are in alinement and ball 64 is biased into seating engagement with recess 58 by the biasing means including spring 66. The spanning at this time by the ball 64 of the interface between shank 12 and tip 14, and specifically the spanning of surfaces 38 and 54 of this interface, has been found quite sufficient to prohibit accidental disengagement of tip 14 from shank 12 while hammer 10 is in use. As pointed out here-inbefore, such accidental disengagement could occur only by movement of tip 14 parallel to the axis of the bore 20 which receives the supporting hammermill shaft, and the forces normally exerted upon the tip while hammer 10 is in use are not such as to tend to move the ti in such a direction, but rather in directions in which its movement is opposed by the tongue and groove means 16 forming the primary interconnection between the tip and the shank. When, however, it is desired to disconnect tip 14 from shank 12 in order to reverse or replace the same, such may be readily accomplished merely by sliding the tip relative to the shank longitudinally of tongue and groove means 16. Asthis movement commences, ball 64 is forced inwardly against the bias of spring 66 by the curved surface and periphery of recess 58 and by the surface 54 of groove 48. Once recesses 56, 58 are out of alinement and ball 64 is unseated from the latter, spring 66 biases the ball into engagement with surface 54 of the tip during the remainder of the sliding movement necessary to fully disconnect the tongue and groove means 16. In addition to facilitating initial unseating, the rotative movement of which ball 64 is capable insures that this remaining sliding movement of tip 14 is in no way impeded. After tip 14 and shank 12 are fully disconnected, the former is reversed, and then is reconnected to the latter in substantially the same manner. No tools or extraneous devices of any type are necessary in order to connect tip 14 to shank 12 or disconnect it therefrom, and neither is it necessary for shank 12 to be removed from or pivoted relative to the supporting hammermill shaft in order to accomplish such connection or disconnection.

It will be noted that during the period while the tip and shank are disconnected there is no possibility of any of the components of hammer 10 being lost or misplaced, since all are permanently associated with and connected to the shank and tip. Further, by reason of their internal location, it will be appreciated that the various components of detent means, 18 are not susceptible to damage or breakage at any time. Also contributing to the trouble-free operation and long useful life of the detent means 18 is the fact that ball 64 and lip 62 of housing 60 effectively seal the open end of the housing and thus prevent foreign matter, which if present would impede movement of ball 64 and the action of spring 66, from entering the housing.

It will thus be seen that there has been provided an impact hammer realizing the objects and possessing the benefits hereinbefore noted, together with many practical advantages. While in the drawing and specification there has been set forth a preferred embodiment of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being defined in the claims.

That which is claimed is:

1. An impact hammer for hammermills and the like comprising an elongate shank member, a reversible tip member, said members having mating interfacial tongue and groove means thereon detachably connecting said tip member to said shank member, said members being slidably connect'able and disconnectable by relative movement in either direction longitudinally of said tongue and groove means and being otherwise restrained against relative movement by said tongue and groove means, and self-releasing detent means traversing the interface between said members for preventing said relative sliding movement therebetween during use of the hammer while permitting said relative sliding'movement when desired to disconnect said members, said detent means comprising a hardened generally spherical element, said members each having an interfacial recess therein adapted when said members are fully connected to be alined and to jointly receive said spherical element, one of said recesses having a curved surface mating with and seating a minor portion of said spherical element, means mounting said spherical element in the other of said recesses for movement transversely of and through said interface, and means in said other recess biasing said spherical element through said interface and into seating engagement with said one recess when said members are fully connected.

2. An impact hammer as in claim 1, wherein said means mounting said spherical element includes a tubular housing disposed within said recess and having an open end communicating with said interface, and wherein said spherical element and said biasing means are located within said housing.

3. An impact hammer as in claim 2, and further including an inturned lip integral and co-extensive with the open end of said housing, and wherein the inner diameter of said housing at said lip is no greater than the outer diameter of said spherical element, whereby said spherical element is retained within said housing by said lip.

4. An impact hammer for hammermills and the like comprising an elongate shank member having a transverse bore extending through its inner end for reception of a hammermill shaft and having an integral elongate section extending at its end substantially parallel to the axis of said bore, a reversible tip member approximately equal in length to said elongate section of shank member, said tip member and said elongate section of said shank member having mating interfacial tongue and groove means extending longitudinally thereof and detachably connecting said tip member to said shank member, same members being slidably connectable and disconnectable by moving said tip member relative to said shank member in either direction longitudinally of said tongue and groove means and said members being otherwise restrained against relative movement by said tongue and groove means, and self-releasing detent means traversing the interface between said members for preventing said relative sliding movement therebetween during use of the hammer while permitting said relative sliding movement when desired to disconnect said tip member from said shank member, said detent means comprising a hardened ball element, said members each having an interfacial recess therein adapted when said members are fully connected to be alined and to jointly receive said ball element, one of said recesses having a curved surface mating with and seating a minor portion of said ball element, a tubular housing mounted within the other of said recesses and having an open end communicating with the interface between said members, said ball element being mounted within said housing for rotative movement and for movement transversely of and through the interface between said members, and spring means in said housing biasing said ball element through the interface between said members and into seating engagement with said one recess when said members are fully connected.

5. An impact hammer as in claim 4, wherein said elongate section of said shank member is of generally rail-like shape including an innermost flange portion and i an outermost head portion interconnected by an integral web portion, and wherein said tip member has a centrally disposed undercut groove extending the entire length thereof, and said tongue and groove means detachably connecting said members includes said undercut groove of said tip member and said portions of said raillike elongtae section of said shank member.

6. An impact hammer as in claim 4, wherein the other of said recesses is within said shank member, and wherein said housing is mounted press-fit therein and includes an inturned lip integral and co-extensive with said open end thereof, the inner diameter of said housing at said lip being no greater than the outer diameter of said ball element, whereby said ball element is retained within said housing by said lip.

7. An impact hammer as in claim 4, wherein said elongate section is of generally rail-like shape and includes an innermost flange portion and an outermost head portion interconnected by an integral web portion, and wherein said tip member is of generally rectangular shape having opposed innermost and outermost faces and opposed front and rear faces, said tip member having a groove extending centrally along the entire length of said innermost face thereof and said groove having an innermost portion and an undercut outermost portion communicating with said innermost portion, said tongue and groove means including said head and web portions of said elongate member and said groove of said tip member, and wherein said tip member further includes flared projections formed integral with and extending from the outermost areas of said front and rear faces thereof.

References Cited by the Examiner UNITED STATES PATENTS 2,568,077 9/51 Loufek 241-197 2,620,989 12/52 Keiper 241197 3,036,839 5/ 62 Williamson 279-76 X 3,141,692 7/64 Behrens 292147 FOREIGN PATENTS 361,214 5/62 Switzerland.

J. SPENCER OVERHOLSER, Primary Examiner. 

1. AN IMPACT HAMMER FOR HAMMERMILLS AND THE LIKE COMPRISING AN ELONGATE SHANK MEMBER, A REVERSIBLE TIP MEMBER, SAID MEMBERS HAVING MATING INTERFACIAL TONGUE AND GROOVE MEANS THEREON DETACHABLY CONNECTING SAID TIP MEMBER TO SAID SHANK MEMBER, SAID MEMBERS BEING SLIDABLY CONNECTABLE AND DISCONNECTABLE BY RELATIVE MOVMENT IN EITHER DIRECTION LONGITUDINALLY OF SAID TONGUE AND GROOVE MEANS AND BEING OTHERWISE RESTRAINED AGAINST RELATIVE MOVEMENT BY SAID TONGUE AND GROOVE MEANS, AND SELF-RELEASING DETENT MEANS TRAVERSING THE INTERFACE BETWEEN SAID MEMBERS FOR PREVENTING SAID RELATIVE SLIDING MOVEMENT THEREBETWEEN DURING USE OF THE HAMMER WHILE PERMITTING SAID RELATIVE SLIDING MOVEMENT WHEN DESIRED TO DISCONNECT SAID MEMBERS, SAID DETENT MEANS COMPRISING A HARDENED GENERALLY SPHERICAL ELEMENT, SAID MEMBERS EACH HAVING AN INTERFACIAL RECESS THEREIN ADAPTED WHEN SAID MEMBERS ARE FULLY CONNECTED TO BE ALINED AND TO JOINTLY RECEIVE SAID SPHERICAL ELEMENT, ONE OF SAID RECESSES HAVING A CURVED SURFACE MATING WITH AND SEATING A MINOR PORTION OF SAID SPHERICAL ELEMENT, MEANS MOUNTING SAID SPHERICAL ELEMENT IN THE OTHER OF SAID RECESSES FOR MOVEMENT TRANSVERSELY OF AND THROUGH SAID INTERFACE, AND MEANS IN SAID OTHER RECESS BIASING SAID SPHERICAL ELEMENT THROUGH SAID INTERFACE AND INTO SEATING ENGAGEMENT WITH SAID ONE RECESS WHEN SAID MEMBERS ARE FULLY CONNECTED. 